The usage of image trigonometry in bone measurements.

The entire musculo-skeletal system responds dynamically to stresses and strains applied to it. Restoring normal biomechanics contributes to the normal function that ensures that physiological stresses and strains are preserved. Appropriate preoperative planning is mandatory to restore normal biomechanics at reconstructive surgery. Effective preoperative planning depends on the ability to reproducibly make accurate measurements of lengths and angles from plain radiographs. Measurement has become an integral part of orthopaedics to define morphological abnormality, to plan for reconstruction and for comparative research. The most prevalent method of measurement is usually based on lines drawn on radiographs with no accurate reference to the actual geometry of the structures. This two-dimensional projection of an asymmetrical three-dimensional structure leads to inaccuracy and consequently to a compromise in the overall precision of many procedures. In addition it is also difficult to monitor the progression of disease as the exact relationship of the bones and joints to each other, and to prosthetics, cannot be accurately recorded. This paper presents a method of digitally measuring relevant bone parameters in a geometric manner in order to achieve accurate, repeatable measurements.

Blood levels of cobalt and chromium are inversely correlated to head size after metal-on-metal resurfacing arthroplasty.

Resurfacing arthroplasty has fallen out of favour in recent years due to unfavourable survivorship in joint registries and alarming reports of soft tissue reactions around metal on metal prostheses. Our aim was to assess the effect of head size, implant design and component positioning on metal production by resurfacing arthroplasties. We measured whole blood cobalt and chromium and component position in matched populations implanted with two designs of resurfacing arthroplasty over a two-year period. Both implants resulted in a significant increase in blood metal levels (p<0.001) though the ASR design generated significantly higher metal levels (p = 0.041). A significant inverse correlation was seen between component size and blood cobalt levels (p = 0.032) and blood chromium levels (p<0.001). No correlation was identified between component position and blood metal levels. Small diameter metal resurfacing components result in increased metal generation compared with larger components. As increased metal generation has been correlated to wear and therefore failure, caution must be used on implantation of smaller components and indeed, in those who require smaller components, alternative bearing materials should be considered. These results contrast with recent findings which have demonstrated early failure for larger diameter stemmed metal-on-metal prostheses.

Primary and revision THA using a stemless metaphyseal-loading implant above distorted proximal femoral anatomy.

Total hip arthroplasty is well established as a successful treatment for end stage arthritis, with a wide variety of components currently available. Using traditional stemmed implants in patients with a distorted proximal femur can be technically challenging with an increased risk of complications. We present seven patients with distorted proximal femoral anatomy or failed hip arthroplasty in whom a short, metaphyseal loading implant was utilised. At minimum two-year follow-up there have been no complications with all stems stable and well fixed radiologically. Average improvement in Oxford Hip Score is 32. We suggest that a short, metaphyseal loading prosthesis can be considered in cases where a conventional stemmed implant may not be suitable due to challenging proximal femoral anatomy.

Medium-term outcome in patients treated with total hip arthroplasty using a modular femoral stem.

The clinical, radiographic and quality of life results of total hip arthroplasty using the MODULUS cementless modular femoral stem were reviewed. 48 patients who had a total hip arthroplasty using the MODULUS femoral stem were identified. Six had bilateral procedures, resulting in 60 hips with complete clinical and radiographic data. Mean age at implantation was 50 years (range 33 to 82). Mean follow-up was 59 months (range 50 months to 73). There were two early post-operative dislocations (within 2 days). One patient required further surgery to remove heterotopic bone. Mean Harris Hip Score increased from 37 points preoperatively (range, 7 to 66) to 89 points at final review (range, 65 to 100 points). Radiographic evaluation revealed that all implants were stable without evidence of osteolysis but three patients (5%) exhibited heterotopic ossification. Quality of life was evaluated with the SF36. The physical component increased from 29.2 points (range, 18.5 to 46.0) to 51.7 points (range 42.9 to 60.6) and the mental component from 375 points (range, 19.5 to 50.0) to 50 points (range 32,8 to 62.0).

Somatosensory abnormalities in knee OA.

OBJECTIVE: The aim of this study was to use quantitative sensory testing (QST) to explore the range and prevalence of somatosensory abnormalities demonstrated by patients with advanced knee OA. METHODS: One hundred and seven knee OA patients and 50 age- and sex-matched healthy participants attended a 1-h QST session. Testing was performed on the medial side of the knee and the pain-free forearm. Light-touch thresholds were assessed using von Frey filaments, pressure pain thresholds using a digital pressure algometer, and thermal sensation and pain thresholds using a Thermotest MSA. Significant differences in median threshold values from knee OA patients and healthy participants were identified using Mann-Whitney U-tests. The z-score transformations were used to determine the prevalence of the different somatosensory abnormalities in knee OA patients. RESULTS: Testing identified 70% of knee OA patients as having at least one somatosensory abnormality. Comparison of median threshold values between knee OA patients and healthy participants revealed that patients had localized thermal and tactile hypoaesthesia and pressure hyperalgesia at the osteoarthritic knee. Tactile hypoaesthesia and pressure hyperalgesia were also present at the pain-free forearm. The most prevalent somatosensory abnormalities were tactile hypoaesthesia and pressure hyperalgesia, evident in between 20 and 34% of patients. CONCLUSION: This study found that OA patients demonstrate an array of somatosensory abnormalities, of which the most prevalent were tactile hypoaesthesia and pressure hyperalgesia. Further research is now needed to establish the clinical implications of these somatosensory abnormalities.

Conversion of a long distally fixed uncemented revision femoral stem to a proximally fixed implant following fatigue fracture.

There has been increasing focus on bone conservation through proximal fixation in primary hip arthroplasty. However, the debate regarding fixation in revision arthroplasty and which factors influence implant choice remains less clear-cut. We report a case involving fatigue fracture of a long, distally well-fixed, uncemented revision stem. This was revised to a proximally fixed implant. This case highlights a number of issues when considering the choice of implant in hip revision surgery and raises the issue of bone conservation in revision surgery. We would suggest that in both primary and revision hip arthroplasty meticulous pre-operative consideration of the choice of implant should be undertaken, especially in the younger patient with higher expectations and functional demands.

Persistent pain after joint replacement: prevalence, sensory qualities, and postoperative determinants.

Persistent postsurgical pain is a prevalent but underacknowledged condition. The aim of this study was to assess the prevalence, sensory qualities, and postoperative determinants of persistent pain at 3 to 4years after total knee replacement (TKR) and total hip replacement (THR). Patients completed a questionnaire with included the Western Ontario and McMaster Universities Index of Osteoarthritis (WOMAC) Pain Scale, PainDetect Questionnaire, Short-Form McGill Pain Questionnaire, and questions about general health and socioeconomic status. A total of 632 TKR patients and 662 THR patients completed a questionnaire (response rate of 73%); 44% of TKR patients and 27% of THR patients reported experiencing persistent postsurgical pain of any severity, with 15% of TKR patients and 6% of THR patients reporting severe-extreme persistent pain. The persistent pain was most commonly described as aching, tender, and tiring, and only 6% of TKR patients and 1% of THR patients reported pain that was neuropathic in nature. Major depression and the number of pain problems elsewhere were found to be significant and independent postoperative determinants of persistent postsurgical pain. In conclusion, this study found that persistent postsurgical pain is common after joint replacement, although much of the pain is mild, infrequent, or an improvement on preoperative pain. The association between the number of pain problems elsewhere and the severity of persistent postsurgical pain suggests that patients with persistent postsurgical pain may have an underlying vulnerability to pain. A small percentage of patients have severe persistent pain after joint replacement, and this is associated with depression and the number of pain problems elsewhere.

Unstated factors in orthopaedic decision-making: a qualitative study.

BACKGROUND: Total joint replacement (TJR) of the hip or knee for osteoarthritis is among the most common elective surgical procedures. There is some inequity in provision of TJR. How decisions are made about who will have surgery may contribute to disparities in provision. The model of shared decision-making between patients and clinicians is advocated as an ideal by national bodies and guidelines. However, we do not know what happens within orthopaedic practice and whether this reflects the shared model. Our study examined how decisions are made about TJR in orthopaedic consultations. METHODS: The study used a qualitative research design comprising semi-structured interviews and observations. Participants were recruited from three hospital sites and provided their time free of charge. Seven clinicians involved in decision-making about TJR were approached to take part in the study, and six agreed to do so. Seventy-seven patients due to see these clinicians about TJR were approached to take part and 26 agreed to do so. The patients' outpatient appointments ('consultations') were observed and audio-recorded. Subsequent interviews with patients and clinicians examined decisions that were made at the appointments. Data were analysed using thematic analysis. RESULTS: Clinical and lifestyle factors were central components of the decision-making process. In addition, the roles that patients assigned to clinicians were key, as were communication styles. Patients saw clinicians as occupying expert roles and they deferred to clinicians' expertise. There was evidence that patients modified their behaviour within consultations to complement that of clinicians. Clinicians acknowledged the complexity of decision-making and provided descriptions of their own decision-making and communication styles. Patients and clinicians were aware of the use of clinical and lifestyle factors in decision-making and agreed in their description of clinicians' styles. Decisions were usually reached during consultations, but patients and clinicians sometimes said that treatment decisions had been made beforehand. Some patients expressed surprise about the decisions made in their consultations, but this did not necessarily imply dissatisfaction. CONCLUSIONS: The way in which roles and communication are played out in decision-making for TJR may affect the opportunity for shared decisions. This may contribute to variation in the provision of TJR. Making the importance of these factors explicit and highlighting the existence of patients' 'surprise' about consultation outcomes could empower patients within the decision-making process and enhance communication in orthopaedic consultations.

Evaluation of the Personal Impact Health Assessment Questionnaire (PI HAQ) to capture the impact of disability in osteoarthritis.

AIM: Measuring facts about disability may not reflect their personal impact. An individualized values instrument has been used to weight difficulty in performing activities of daily living in rheumatoid arthritis, and calculate personal impact (Personal Impact Health Assessment Questionnaire; PI HAQ). This study aimed to evaluate the PI HAQ in osteoarthritis (OA). STUDY DESIGN: Study 1: 51 people with OA completed short and long versions of the value instrument at 0 and 1 week. Study 2: 116 people with OA completed the short value instrument, disability and psychological measures at 0 and 4 weeks. RESULTS: Study 1: The eight-category and 20-item value instruments correlated well (r = 0.85) and scores differed by just 2.7%. The eight-category instrument showed good internal consistency reliability (Cronbach's alpha = 0.85) and moderate one-week test-retest reliability (r = 0.68, Wilcoxon signed-rank test p = 0.16, intra-class correlation coefficient [ICC] 0.62). Study 2: Values for disability were not associated with disability severity or clinical status. After weighting disability by value, the resulting PI HAQ scores were significantly associated with dissatisfaction with disability, perceived increase in disability, poor clinical status and life dissatisfaction, and differed significantly between people with high and low clinical status (convergent and discriminant construct validity). There was moderate association with the disease repercussion profile disability subscale (r = 0.511; p < 0.001) (criterion validity). The PI HAQ was stable over four weeks (ICC 0.81). CONCLUSIONS: These studies provide an initial evaluation of an instrument to measure the personal impact of disability in people with OA, setting disability within a personal context. Further studies, including sensitivity to change, are required.

Conservative stems in total hip replacement.

Arthritis of the hip primarily involves the joint surfaces. Intuitively the principal objective in the surgical management of arthritis is to replace the damaged articular surfaces. However, early attempts at conservative replacement failed both because of inadequate fixation and failure of the articulation.Conservative hip implants take less bone at the time of surgery and preserve bone in the longer term with more physiological loading. In addition, the implants are usually easier to insert with soft tissue sparing surgery. While these implants potentially offer an additional option in the surgical management of younger patients with arthritis, this advantage is negated if there is an unacceptably high incidence of premature failure. This paper explores the evolution and results of conservative total hip prostheses that culminated in the contemporary designs.

Periprosthetic DXA after total hip arthroplasty with short vs. ultra-short custom-made femoral stems: 37 patients followed for 3 years.

BACKGROUND AND PURPOSE: Dual-energy X-ray absorptiometry (DXA) analysis of the 7 periprosthetic Gruen zones is the most commonly used protocol to evaluate bone remodeling after the implantation of conventional femoral stems. We assessed the value of DXA after cementless primary total hip arthroplasty (THA) by comparing the effect of progressive shortening of the stem of two femoral implants on periprosthetic bone remodeling using a specifically developed protocol of analysis with 5 periprosthetic regions of interest (ROIs). PATIENTS AND METHODS: Bone mineral density (BMD) was evaluated in 37 patients in the plateau stage, 3 years after THA. Two femoral implants featuring conceptually new designs and surgical technique were tested: types 1 and 2, characterized by extremely short stem and virtual absence of distal stem, respectively. RESULTS: We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time. In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5. No differences were found in ROIs 1, 2, and 3. INTERPRETATION: This study shows the flexibility of DXA in adapting the protocol of periprosthetic analysis to the specific requirements of new implant designs, and it shows its high sensitivity in evaluation of the biological response of bone to changes in implant shape.

Impaction bone grafting of the acetabulum at hip revision using a mix of bone chips and a biphasic porous ceramic bone graft substitute.

BACKGROUND AND PURPOSE: One of the greatest problems of revision hip arthroplasty is dealing with lost bone stock. Good results have been obtained with impaction grafting of allograft bone. However, there have been problems of infection, reproducibility, antigenicity, stability, availability of bone, and cost. Thus, alternatives to allograft have been sought. BoneSave is a biphasic porous ceramic specifically designed for use in impaction grafting. BoneSave is 80% tricalcium phosphate and 20% hydroxyapatite. Previous in vitro and in vivo studies have yielded good results using mixtures of allograft and BoneSave, when compared with allograft alone. This study is the first reported human clinical trial of BoneSave in impaction grafting. METHODS: We performed a single-institution, multi-surgeon, prospective cohort study. 43 consecutive patients underwent revision hip arthroplasty using BoneSave and allograft to restore missing bone in the acetabulum. 9 patients had cemented acetabular components implanted and 34 uncemented. 10 patients had cemented femoral components implanted and 1 had an uncemented femoral component. 32 patients did not have their femoral component revised. RESULTS: No patients were lost to follow-up. At a mean follow-up of 24 (11-48) months, there were no re-revisions and there was no implant migration. 1 acetabular component had confluent lucent lines at the implant-graft interface. Complications were rare (1 fracture, 2 dislocations). Patient satisfaction with the procedure was high. INTERPRETATION: Short-term results indicate that impaction grafting of BoneSave and allograft is an effective method of dealing with loss of bone stock at revision hip surgery.

Use of irradiated bone graft for impaction grafting in acetabular revision surgery: a review of fifty consecutive cases.

Impaction bone grafting is a useful technique in the armament of a revision hip surgeon. Traditionally fresh frozen allograft has been used for this technique. However there are concerns about the transmission of viral proteins and prions through this form of allograft. As a result irradiated bone graft has been favoured in some centres. There is no long term series describing the results of impaction bone grafting using irradiated bone. This paper reviews a consecutive series of 50 cases of acetabular revision surgery performed between 1995 and 2001 and followed up over a mean period of 45 months. The preoperative bone defect was graded by the Paprosky classification. There were 2 cases of type 1a, 9 type 2a, 15 type 2b, 7 type 2c, 10 type 3a and 7 type 3b. All cases were followed up clinically and radiologically. Case notes were reviewed for primary prosthesis, operative details and reason for revision. The radiographs were evaluated for signs of bone incorporation, remodelling, loosening and migration of the acetabular component. There were 5 cases of aseptic loosening at the end of the follow up period. One patient had recurrent dislocation and was revised. 20 cases (40%) showed changes suggestive of bone incorporation, while only 3 cases (6%) showed remodelling. Clinically a good or excellent outcome with absence of pain was achieved in 35 patients (70%). The results suggested that acetabular impaction bone grafting using irradiated bone graft is comparable to fresh frozen allograft. The low percentage of remodelling remains a concern and warrants further studies.

A new short uncemented, proximally fixed anatomic femoral implant with a prominent lateral flare: design rationals and study design of an international clinical trial.

BACKGROUND: Anatomic short femoral prostheses with a prominent lateral flare have the potential to reduce stress-shielding in the femur through a more physiological stress distribution to the proximal femur. We present the design rationale of a new short uncemented, proximally fixed anatomic femoral implant and the study design of a prospective multi-centre trial to collect long-term patient outcome and radiographic follow up data. METHODS: A prospective surveillance study (trial registry NCT00208555) in four European centres (UK, Italy, Spain and Germany) with a follow up period of 15 years will be executed. The recruitment target is 200 subjects, patients between the ages of 18 and 70 admitted for primary cementless unilateral THA will be included. The primary objective is to evaluate the five-year survivorship of the new cementless short stem. The secondary objectives of this investigation are to evaluate the long term survivorship and the clinical performance of the implant, the impact on the subjects health related Quality of Life and the affect of the prosthesis on bone mineral density. Peri- and postoperative complications will be registered. Clinical and radiographic evaluation of prosthesis positioning will be done post-operatively and at 3, 6, 12, 24, 60, 120 and 180 months follow up. DISCUSSION: Shortening of the distal stem can maximise bone and soft tissue conservation. New stem types have been designed to improve the limitations of traditional implants in primary THA. A new, uncemented femoral short stem is introduced in this paper. A long-term follow up study has been designed to verify stable fixation and to research into the clinical outcome. The results of this trial will be presented as soon as they become available.

A systematic comparison of the actual, potential, and theoretical health effects of cobalt and chromium exposures from industry and surgical implants.

Humans are exposed to cobalt (Co) and chromium (Cr) from industry and surgical devices, most notably orthopedic joint replacements. This review compares the potential health effects of exposure to Co and Cr contaminants from these two different sources, both in the locally exposed tissues and at sites distant to the primary exposure. Surgical implantation results largely in exposures to ions, corrosion products, and particles of Co and Cr. Industrial exposures are predominantly to metal compounds and particles. Although there are large literatures on industrial and surgical exposures to these metals, there has yet to be a systematic comparison of the two to test whether more general lessons might be learned about the human toxicology of Co and Cr. Both industrial and surgical exposures cause inflammatory and other immune reactions in the directly exposed tissues. In the lung there is a well-established risk of cancer following long-term exposures to hexavalent Cr; however, the development of sarcoma in the connective tissues adjacent to implants in response to metal particles is rare. Both types of exposure are associated with changes in the peripheral blood, including evidence of oxidative stress, and altered numbers of circulating immune cells. There is dissemination of Co and Cr to sites distant to the orthopedic implant, but less is known about systemic dissemination of these metals away from the lung. The effects of industrial exposures in the reproductive, renal, and cardiac systems have been investigated, but this has yet to be explored after surgical exposures. The form of the metal (and associated elements) in both instances is key to the toxicological effects arising in the body and further characterization of debris released from devices is certainly recommended, as is the impact of nanotoxicology on the health and safety of workers and patients. Biomonitoring schemes currently used in industry could be translated, if required, into suitable programs for orthopedic out-patients. Cross-communication between experts in industrial and occupational medicine and regulatory agencies may be useful.

The operation of the century: total hip replacement.

In the 1960s, total hip replacement revolutionised management of elderly patients crippled with arthritis, with very good long-term results. Today, young patients present for hip-replacement surgery hoping to restore their quality of life, which typically includes physically demanding activities. Advances in bioengineering technology have driven development of hip prostheses. Both cemented and uncemented hips can provide durable fixation. Better materials and design have allowed use of large-bore bearings, which provide an increased range of motion with enhanced stability and very low wear. Minimally invasive surgery limits soft-tissue damage and facilitates accelerated discharge and rehabilitation. Short-term objectives must not compromise long-term performance. Computer-assisted surgery will contribute to reproducible and accurate placement of implants. Universal economic constraints in healthcare services dictate that further developments in total hip replacement will be governed by their cost-effectiveness.

Genotoxic effects of particles of surgical cobalt chrome alloy on human cells of different age in vitro.

Humans are exposed to metals from industry, the environment and from wear debris from worn orthopaedic joint replacements. Patients exposed to worn cobalt chrome hip replacements show an increase of chromosome aberrations in the bone marrow adjacent to the implant and an increase of chromosome translocations and aneuploidy in the peripheral blood. This study has tested whether particles of surgical cobalt chrome alloy are able to induce similar DNA damage and chromosome aberrations in human cells in vitro. Because increasingly young patients are receiving hip replacements it has also tested whether the response is altered at different cellular age in vitro. Primary human fibroblasts, were tested at different pre senescent population doublings (PD10 (young) and PD35 (older)) to particles of cobalt chrome alloy for up to 15 days. As in patients there was an increase of aneuploidy, chromosome translocations and DNA damage after exposure to the cobalt chrome particles in vitro. The overall level of DNA damage and numerical and structural aberrations was approximately the same in young and older cells. However, the cellular reaction to the DNA damage was different. Older cells showed a greater loss of viability and induction of senescence and a lesser rate of mitosis and cell growth than young cells. They showed less change in transcription, particularly of p38 and caspase 10 mRNA levels, than young cells. They showed more complex aneuploidy in association with unseparated or prematurely separated chromatids. This study suggests that at least part of the chromosome changes in patients with worn implants may be due to direct effects of the metal wear particles from the implant. It would be of interest to test whether the altered reaction of the human cells at different in vitro age might correspond with a different incidence of chromosome aberrations in patients at different ages.